Ian Savage and Burgess Scott (2004). Deploying regional jets to add new spokes to a bub. Journal of Air Transportation Management 10(2):147-150.
[Journal Website]  [Manuscript Version]

A common use of regional jets has been to add new spokes to existing hubs. This paper estimates a model to explain the 36 new links that were added by Delta Air Lines affiliate Comair to its Cincinnati / Northern Kentucky Airport hub between 1996 and 2001. Distance, population of the spoke city, and number of flights offered through alternative hubs were strong predictors of new service. The coefficients of the model were validated by using them to predict new links added over the same period at Atlanta, Georgia. The majority of these new routes were operated by regional jets owned by another Delta affiliate, Atlantic Southeast Airlines.

You can also view an appendix table containing the predicted results for regional jet deployment in Atlanta. This table was not included in the published paper to save space [3 pages, 70 kb PDF].